Julian Lewis is stumped. The newly elected chair of the Defence Select Committee is sitting in his parliamentary office, struggling to get his head around the Government’s position on Defence spending. The towers of well-thumbed books and reports on Defence which fill the room, piled high on his desk, shelves, cabinets and even his armchair, are testament to the deep thinking on the topic which Lewis prides himself on. He’s written countless pamphlets and articles over the past three decades – many of which are pressed eagerly into this interviewer’s hands – and few people in the Commons can boast such a thorough commitment to understanding a policy area as he.

Yet the continued refusal from Ministers to reveal whether they will commit to spending the NATO target of 2% of GDP on Defence beyond 2016 has left him utterly mystified. “I’m baffled about it,” he exclaims.

“The idea that we would drop below the minimum of 2% is just unconscionable as far as I’m concerned.”

All three candidates in the Defence Committee chair election – which Lewis won in the second round last week by 314 votes to Richard Benyon’s 242 – strongly backed a fresh pledge to meet the target, and Lewis says he now feels a “sense of a strong mandate” to press the case after his victory. And for someone long considered one of the Government’s fiercest critics on Defence – his own website quotes testimonials from the Guardian describing him as a “terrier” and the Daily Telegraph labelling him “one of the most vigorous Right-wingers in the Commons” – the early signs are he won’t be rescinding his membership of the Conservative 'Awkward Squad' despite his new position.

Defence, he says,

“has fallen far too low in the nation’s scale of priorities. The Government has got to justify the safeguarding and ring-fencing of budgets for other departments whilst leaving Defence unprotected, and they have to justify this in the light of the constant and reiterated claim that Defence is ‘the first duty of government’. Well if Defence is the first duty of government why is its budget unprotected whilst the budgets of other departments are ring-fenced?

“We’re facing both an international terrorist offensive and a more traditional threat from a potentially hostile state. Personally, in view of the worsening situation, I think we ought to be looking more towards a figure approaching 3%.”

A final decision on 2% will have to be made by the autumn when the Government carries out its fresh Strategic Defence and Security Review, and the Treasury publishes its Whitehall-wide Spending Review. Lewis was a strong critic of the last SDSR back in 2010, describing it as “unstrategic” and suggesting it was fiscally-led at the expense of a serious piece of analysis of the threats facing Britain. He fears the Government is already set to repeat the mistake.

“I think the next one will be done in exactly the same way as the last one was,” he says. “[The Government] appears to have said ‘Here is a certain sum of money, this is all you’re getting, how much Defence can you give me within that’ – to use the horrible jargon – ‘financial envelope’?

“But if you don’t at least understand what it is you really want and need according to the actual and potential dangers which could and do face you, it is just an absurdity to say you are only going to get this sum of money irrespective, and you just have to make the best use of it that you can.

“Ok it may be the case that not everything that we might want in an idea world for Defence is affordable. But you have to examine the threats, list the requirements and then you start arguing with the money men about how many you must have now, how many you can postpone without too much risk and how many you’re unlikely to be able to get funded at all. The idea that these two things are going to happen in perfect synchronisation, publishing the Defence Review in the same instant as the Comprehensive Spending Round … I’m not satisfied that, behind the scenes, the sort of in-depth conversations that need to be carried out in order to get the balance right will have taken place.”

Unless the MoD commits to a sufficient level of Defence spending, he fears, the very basis of NATO’s decades-long strategy itself would be at risk.

“We could always say ‘Ok we’re going to resign from this sort of role, we’re going to put our future in the hands of our potential enemies’. But your potential enemies have a vote as well. It’s not a question of ‘do we give up our role as doing this, that or the other’. We don’t seek out aggression, aggression seeks us out more often than not.

“The reality is that because of our geographical position the UK is in a unique strategic situation as the bridge between Europe and the ultimate guarantor of European security, which is the United States. If the UK were to resign from its role in providing that necessary link then the whole basis for a successful defensive and deterrent strategy by NATO would be fatally undermined.”

But while he is a strong proponent of meeting the NATO target of 2%, he also has serious concerns about the direction of the Alliance. He warns that a “very liberal sprinkling around of offers to be put on the path to join”, particularly recent overtures from European partners towards potential new members in the east, will lead to the alliance being “devalued”.

“The NATO guarantee means that if anyone attacks a single member of the Alliance all the others would be prepared to start World War Three to defend it. If you admit to NATO countries where it is simply not credible to believe that we would start World War Three to defend them, then you completely undermine the whole raison d’etre of the Alliance, and you transport us at a stroke back to the 1930s when potentially aggressive states could try picking off one weak country after the other in the hope that stronger countries would not come to their aid.”

The NATO guarantee has already, he continues, been “stretched to its absolute credible limit” with the accession of the Baltic States. The recent development of closer ties with other former Soviet states could prove “terribly dangerous”, he warns.

“During the Cold War years we did not have a policy of egging on countries that were clearly under Russian domination into rising up against that, because we knew that we were not in a position to assist them if then they were subject to a military attack. The idea of saying we will give security guarantees to countries such as Georgia and Ukraine is not doing them any favours, because it’s egging them on into taking a stance where they will simply find themselves exposed while still being incapable of being defended.”

For that reason, he continues, he is also “totally hostile” to the idea of any European Defence Force “of any sort whatsoever”.

“That is trying to re-create and duplicate NATO, without the one key element that makes NATO worth having which is the membership of the United States,”

he says.

“The whole point of NATO, and it’s as simple as this, is to say you touch any one of these countries and you are automatically at war with all of the rest, including the United Kingdom, and above all it means you cannot pick off any of these countries without instantly being at war with the United States. That is the great deterrent.

“If you weaken that deterrent, either by taking countries into membership where it is simply not credible to believe that all these other countries including the United States would start World War Three to defend it, or alternatively if you create structures that start trying to act as if they’re a unity, but which exclude the biggest deterrent factor of all to an aggressor intent on grabbing territory – that he will be at war with the US from Day One – then you are cutting across and countermanding the whole basis and merit and virtue of the NATO alliance in the first place.

“It is this sort of infantile posturing by Europeans trying to pretend that they can defend themselves without the underpinning of the Americans and to a lesser but still significant extent the British, which is so deadly dangerous.”

The New Forest East MP – one of his party’s leading Eurosceptics – goes further:

“Although it is sometimes said that the EU has prevented war in Europe, this is nonsense. There was a danger of war in Europe but that was the danger posed by the Soviet Bloc, and the EU did nothing to prevent that, it was NATO that prevented that.

“There was never any prospect of war in Europe between the states that make up the EU as long as they remained constitutional democracies. There are countless cases of democracies going to war with dictatorships, dictatorships going to war with dictatorships, dictatorships going to war with democracies. But there are hardly any credible examples of a democracy going to war with another democracy.

“So what is the danger to the peace of Europe? The danger to the peace of Europe is if you change our system of sovereign democratic states to an undemocratic system.

“And indeed I do fear for the peace and stability of Europe. Because if ever they do manage to create this Superstate, I don’t believe they will be able to create it with the consent of the people concerned and I believe that it will necessarily be an undemocratic entity. And the moment you have undemocratic entities you have a danger of conflict.”

As the discussion then turns to the Middle East and the ‘Islamic State’, Lewis says the West must be prepared for a campaign that will last for several years. Comparing the group to Communism and Nazism, he says IS’s strategy is clear: to secure territory “from which to project their imperial ambitions” and then to attempt to engineer “a fifth column” of terrorists in “the countries they regard as their enemies”. The West’s strategy to counter it must be to “contain them abroad” while stepping up efforts to defeat potential terror attacks at home, he says.

“I think given the size of the Muslim population in Great Britain, which is considerable – approaching I think the two million mark – it is actually a matter for celebration that only a very tiny number as a proportion have engaged in what I like to call unIslamic extremism,”

he says.

“But nevertheless there is the potential there, because it only takes very small numbers of people to engage in a terrorist campaign, to cause a disproportionate amount of fear and disruption. We saw this with the Irish Nationalist cause and the IRA.”

Tony Blair’s former Chief of Staff and fixer Jonathan Powell – someone with a great deal of experience dealing with conflict and terrorism in Northern Ireland – recently said the West would eventually have to “start building a channel to” and communicating with elements of IS. Does Lewis agree? He says he sympathises with Winston Churchill’s famous reply when asked in the 1930s why he refused to join others in seeking peaceful coexistence with Hitler’s Nazi Germany. Putting on his best Churchill impression he drawls:

“Churchill is said to have growled: ‘When a mad dog makes a dash for my trousers I shoot him down before he can bite’. In other words there are some people you really can’t negotiate with. Isis is like that.”

But if 'Islamic State' is contained and frustrated, he says, its leaders could eventually seek a solution at the negotiating table.

“You cannot negotiate with these people until they transform themselves into being something different from what they are at the moment.

“If we had continually decapitated the IRA there would have been no leaders with a long enough pedigree to realise that they were never going to succeed in gaining an independent Ireland by force and that therefore they would be far better off to achieve some sort of accommodation with the United Kingdom.

“Often people say ‘Oh well it was thanks to Tony Blair and John Major’s political initiatives that the agreement was reached. Well – actually – no, those political initiatives worked only because for 38 years the British Army had, at considerable sacrifice of blood and treasure, ensured that the violent insurrection that was being mounted did not succeed; and over that very long time you had a generation of IRA leaders gradually maturing and realising that they were never going to get what they hoped for and that therefore they need to settle for something less.

“This is what usually happens with counter-insurgency. The Malayan Emergency, for example, lasted from 1948 to 1960. These irregular wars tend to last much longer than regular ones and usually come to an end, in the end, when the insurgent leaders are worn out.

“If you keep killing off the insurgent leaders so they are constantly replaced, then of course they will never get to that point of realising that they are not going to get where they want to be politically.

“So the strategy is to contain these threats abroad and to wait until the countries concerned are mature and developed enough that alternatives to the ‘devil and the deep blue sea’ at the moment of dictatorship or aggressive, vicious, fundamentalism, are available."